From Gray to Green: Bringing Recycled Water Closer to Home
Author: Chad Kennedy, Landscape Architect
Following years of severe drought, water restrictions, and record reservoir lows, a much needed wet winter kissed the parched California landscape, bringing renewed life and color to a very dull and lifeless landscape. Grassy foothills have returned to their picturesque green, deserts blossomed in the spring with brilliant shows of rare wild flowers and dry creeks and rivers now flow with life giving nectar. What a stark difference the weather can bring in less than a year. Though many are breathing a sigh of relief that the epic California drought is over, the impact was felt so intensely that there is no turning back to the way things were done before. Long gone are the days of unrestricted irrigation, unmetered water, and watered sidewalks. Water stewardship education, water law, and landscape codes were changed in such a way that pre-drought landscapes are not allowed or even feasible. This societal change in how we view water has led to even greater opportunities for positive water management through technologies, and creative thinking about how water is used at the residential level.
The "low hanging fruit" of water conservation, landscape water use, was addressed quite heavily during the drought years and has been drastically reduced in comparison to 10 years ago. On average, Californians use upwards of 50,000 gallons of water per person annually, which is dramatically down from numbers in 2010 that were closer to 63,000 gallons per year1. Landscape irrigation, however, is only one of many uses for water in and around the home. What can be said of the hundreds of thousands of gallons of water used to bath and shower, flush toilets, clean dishes, cook meals, and wash clothes? All of these daily actions require a great deal of water, which is most often clean potable water pumped from groundwater aquifers or treated from surface water sources. One method for addressing these water uses is to focus on the quality of water required for each use and the resulting water quality.
Water Source Requirements- Most of our water use does actually require sanitary potable water in order to avoid health issues (cooking, bathing, etc.), however, some water use does not. Flushing of toilets and outdoor landscape irrigation are two heavy water uses that do not require potable water for complete functionality. Instead, they can utilize alternative water sources such as rain harvesting, runoff collection, and gray water recycling. These water sources have been fairly readily available for commercial applications, but due to filtering and cleansing limitations, have only recently been available for residential applications. One of the major limiting factors of alternative water sources is consistent availability. Rain harvesting and stormwater capture is seasonal in California and requires large storage units for sustained use. Click here for an example. Gray water reuse, on the other hand, can be replenished daily if planned for correctly. In fact, one residential cleansing system on the market today Nexus eWater can provide an additional 72,000 gallons of water annually (based on a 4 bedroom home) at volumes of up to 200 gallons per day for use in toilets and in the landscape.
Infrastructure Requirements- In order to capitalize on the availability of gray water, it needs to be captured before it is deposited into the sewer system. The most likely sources of gray water in a residential structure are the bathroom sinks, bathtubs, showers, and washing machines. Black water sources, such as the kitchen sink, dishwasher, and toilets, should be plumbed directly to the sewer system and not reused. Gray water sources should be plumbed separately from black water with purple pipe and deposited into a cleansing system for re-use. Systems like the Nexus eWater system desoap, filter, and disinfect the water resulting in pressurized clean water. Local codes now allow for the use of this water at the residential level, however each municipality should be consulted as to local limitations. This technology is most easily installed on new construction projects, however, existing plumbing can often be retrofitted to accommodate, provided pipes are somewhat accessible.
Californian's have shown over the past decade that they are serious about water use. This sentiment continues as home owners, home builders, and land developers are embracing these types of technology, incorporating them into our everyday activities and creating a new era in how we view water.
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